1. Field of the Invention
In the production of steel, it is known to expose the metal melt contained in ladles, electric arc furnaces or converters to a vacuum and to use a lance to blow oxygen over the metal surface. The CO partial pressure reduction under vacuum allows decarbonization of high-alloy melts down to the lowest carbon content with simultaneous high chrome yield and without over-oxidations. Maximization of the bath surface along with obtaining the largest possible reaction space in a container are primary objects to achieve a high rate of carbon drop when oxygen is blown, even at high initial carbon contents.
2. Description of the Related Art
Typically the use of a lance to blow oxygen on to a metal melt results in an oxygen jet impinging relatively hard upon a bath surface. Influencing the blown steel may be accomplished by altering the number of blowing nozzles; altering the flow direction of the blowing nozzles; or having the oxygen jet emerge in pulses.
For example, DE-AS 27 09 234 discloses a device for blowing crude iron to steel in an oxygen blowing converter. Control valves within the device can be alternately activated by devices that provide for pulsation of the oxygen jet. However, this reference does not disclose a method of blowing-in oxygen under a vacuum. The primary disadvantage associated with the disclosed blowing arrangement is the use of a separately controlled fluidics control system.
EP 0 081 448 B1 discloses a process and a device for oxidizing a steel bath with an oxygen blowing lance. Use of the lance results in an oxygen jet impinging upon the bath surface at a speed within ultrasonic range. Overall oxygen flow is thereby divided into a hard and a soft jet. Furthermore, the disclosed metal bath operates in an environment with atmospheric pressure.
The disclosed blowing device creates an oxygen jet that impinges upon the surface of the steel bath in a relatively limited area, forming a deep erosion in the bath, and dispersing metal droplets into the gas space above the melt. Further, the oxygen jet cannot be adequately stabilized, thus causing the hard jet to drift within the overall flow.